text: A panel of three judges at the Court of Appeal in London rejected Will Cornick's bid.
  Cornick stabbed Mrs Maguire, 61, seven times as she taught a Spanish class at Corpus Christi Catholic College in Leeds in April.
  Mrs Maguire had taught there for more than 40 years and was due to retire.
  At Leeds Crown Court in November, the 16-year-old was warned he might never be released from prison by a judge who found his pride and lack of remorse over his actions "truly grotesque".
  Passing sentence, Mr Justice Coulson told Cornick, who was 15 at the time of the killing, that he must serve at least 20 years before he is eligible to seek parole but warned him: "It's quite possible that day may never come."
  A panel of three judges at the Court of Appeal in London, headed by the Lord Chief Justice Lord Thomas, rejected Cornick's appeal against the minimum term.
  They said the sentencing judge came to "entirely the right decision".
  In a statement read to the court during Cornick's trial, Mrs Maguire's widower Don described the attack as a "monumental act of cowardice and evil".
  Her sister Denise Courtenay said: "We will never recover from this pain and anguish.
  "No amount of punishment can compensate us for what we have lost."
  Following Mrs Maguire's death on 28 April last year, flowers and messages pinned on the fences outside the school gates stretched for more than 100 metres, and a memorial service at Leeds Town Hall was attended by 1,200 people.